The instant invention relates to the use of carboxylic acid/sulphonic acid copolymers to stabilize soluble manganese ion and its reaction products in desirable forms and reduced particle sizes. Manganous ions are often found in well waters while cooling waters contain primarily the manganic species. Anionic species of carbonate, bicarbonate, sulfite, fluoride, chloride, sulfate, etc., and dissolved oxygen may be present in both waters. Oxygen reaction products of iron, manganese, and aluminum can collect on metal surfaces and accelerate corrosion and reduce heat transfer. The copolymers of the instant invention can keep these reaction products in colloidal/fine, dispersed form rather than the normal flocculant, adherent species. The manganese, thus, remains soluble so that it will not form particles which will precipitate out of solution and form scale. The copolymer of the instant invention, thus, acts as a particle size reducer and inhibitor of undesirable reaction species.